To help accelerate the development of floating offshore wind turbines, DNV KEMA has developed design requirements for floating structures and related systems.

According to Johan Sandberg, head of renewable energy at DNV KEMA, the standard covers a broad range of issues, including safety, philosophy and design principles; site conditions, loads and response; materials and corrosion protection; structural design; design of anchor foundations; floating stability; station keeping; control and mechanical systems; and transport and installation.

DNV anticipates the new guidelines will help ensure safety and reliability in floating wind turbines and give the nascent floating-turbine sector the confidence to continue its development to commercial maturity.

"As demand for wind energy increases, we predict offshore deployments will continue to move into deeper waters, and consequently, there’s a need to establish design standards that will help ensure safety, reliability and confidence in future wind turbines," Sandberg says. "To that end, the new standard, developed as a Joint Industry Project with 10 participating companies, aims to spur progress in floating offshore wind through a framework for best practices and technical requirements, plus producing guidance for design, construction and in-service inspection."

Sandberg notes that many densely populated coastal areas around the world are not suitable for traditional bottom-fixed offshore wind turbines. In other areas, the shallow-water coast is already developed or challenging seabed conditions makes bottom-fixed offshore wind unsuitable. Also, local communities have been known to oppose projects due to negative visual impacts.

"Recent successful deployments of full-scale prototype configurations have demonstrated that floating wind turbines can be a viable alternative, and the market is taking notice. Several companies and research institutes worldwide are already engaged in developing research programs, pilot projects and even planning for commercial development of floating wind farms," Sandberg says.

For various reasons, countries such as Japan and the U.S. have also made offshore wind energy one focus of their energy policy. According to Sandberg, a tricky point in the development of offshore wind in Japan and the U.S. is that water depths can fluctuate from dozens to hundreds of meters.